Water or other liquid present in a substance, a critical factor in food quality, safety, and shelf life. The moisture content of foods ranges from a few percent in crackers to over 90 percent in fresh vegetables, determining texture, weight, and perishability. More important for safety is water activity, the free water available to microorganisms: controlling it through drying, salting, or sugaring preserves foods. Excess moisture causes sogginess, mould, and spoilage, while too little makes foods dry and unpalatable. Manufacturers measure and control moisture precisely, and packaging protects products from gaining or losing it during storage.